Genetic Analysis of Seed-Oil Concentration across Generations and Environments in Sunflower

Abstract

Seed-oil concentration is a major consideration in sunflower (Helianthus annuus L.) breeding because it is an important component of oil yield. Seed-oil concentration is a complex trait determined by the genotype and the environmental conditions. The objectives of this study were (i) to locate quantitative trait loci (QTL) for seed-oil concentration across generations and environments, (ii) to compare QTL detected among individual F2 plants and their F3–generation progeny, and (iii) to assess the genetic relationship between seed-oil concentration and days to flowering in an elite sunflower population. Two hundred thirty-five F2 plants and F3 lines of a single-cross population of two divergent inbred lines were evaluated in four environments. Detection of QTL was facilitated with a genetic map of 205 loci defined by restriction fragment length polymorphism (RFLP) and composite interval mapping. Eight QTL on seven linkage groups accounted for 88% of the genetic variation for seed-oil concentration across environments. Gene action was additive for four QTL and dominant or overdominant at the others. In all environments, the QTL on linkage group G20cM had the most influence on seed-oil concentration. Four of the eight QTL were detected in two or more environments and the parental effects were the same across generations and environments. The phenotypic correlation between seed-oil concentration and days to flower (DTF) ranged from −0.05 to –0.29. QTL on two linkage groups (B and L) affected seed-oil concentration and DTF. The highest LOD score for these two QTL associated with seed-oil concentration was observed at the environment with the highest rate of decline of temperature and radiation during the grain-filling period. Additive effects for higher values of DTF and lower values of seed-oil concentration in linkage groups B and L were derived from the same parent.